Rotary position sensors have long been used in machines of every type, particularly articulated machinery such as robotic arms. Position sensors can be based on shaft encoders, either optical or magnetic for example monitoring a magnetic pattern impressed on a bearing race with a Hall effect or other magnetic sensor. A problem with many sensors is that they simply count pulses of an optical or magnetic nature as one part rotates with respect to another. Such sensors are accurate in determining rotational velocity and can be accurate for position so long as an initial starting position is known. However, in some applications power may be interrupted and so position sensing may require resetting the rotational joint or arm to a zero or calibration position. One type of recently developed sensor is based on Triaxis™ Hall technology from Melexis Microelectronic Integrated Systems NV (Brussels) and uses integrated magnetic concentrators (IMC) to allow 360° position sensing based on the rotation of a magnet with a north-south pole on-axis with an array of four Hall effect sensors. For best accuracy, these types of sensors require a rotating magnet to be relatively accurately positioned over the sensor and of a certain size. In certain applications the advantages of absolute position measurement from when the power is turned on are desirable, while at the same time rotational movement of less than 360° is sufficient. Further a packaging arrangement that measures only rotation in one plane of a shaft that is moving in two planes is desirable.